NTH

the nth element (zero-based) of a list
Major Section:  PROGRAMMING

(Nth n l) is the nth element of l, zero-based. If n is greater than or equal to the length of l, then nth returns nil.

(Nth n l) has a guard that n is a non-negative integer and l is a true-listp.

Nth is a Common Lisp function. See any Common Lisp documentation for more information.